I owned an Aragon 4004 MKII for a very long time and I really enjoyed it immensely.
I have also listened to the McCormack DNA-1, but it was a very long time ago.
The Aragon has enough power to basically drive any speaker. The bass was phenomenal which was it's best quality, it was also deep and tight. The imaging and focus was rock solid, the midrange was good, and the treble was extended. I was using it with a VTL Super Deluxe Preamp, which has a wonderful midrange and was a great match. I'm concerned that if you use it with a SS Preamp then the midrange may be a little dry and the treble may have a slight edge. Dynamics and transients, were also very good. Low level retrieval was fantastic. The soundstage was set back behind the speakers, and it was deep and wide.
The McCormack also had very good bass, but not as rock solid as the Aragon, the midrange was sweeter on the McCormack, I honestly can't remember what the treble sounded like. I heard this amp at the dealers showroom, so I don't recall what preamp was being used. The soundstage wasn't as deep as the Aragon, and it also had a more forward presentation.
I guess your decision should come down to what preamp and speakers you plan on using with either one of these Amps.
So....., what Speakers do you have?